Porous plug for staybolts and the manufacture thereof



March 21, 1939. w. T KILBORN ET AL 2,150,927'

POROUS PLUG FOR STAYBOLTS AND THE MANUFACTURE THEREOF Filed April 30,1936 4 QW V INVENTORS will 0 Patented Mar. 21, 1939 2,150,927

UNITED STATES PATENT OFFICE POROUS PLUG FOR STAYBOLTS AND THEMANUFACTURE THEREOF William T. Kilborn, Pittsburgh, and Frederick K.Landgraf, Crai'ton, Pa., assignors to Flannery Bolt Company,Bridgeville, Pa., a corporation of Delaware Application April 30, 1936,Serial No. 77,186

Claims. (Cl. 85-15) This invention relates to the porous bodies or tothe severe operating conditions of the boiler, plugs which are used inthe firebox end of staythere is also added the jarring and vibrationunbolts to close the opening in said bolts, and to a avoidably incidentto operating over rail Joints, method of making the same. switches, etc.

5 In many boiler installations, it is desirable to It would beimpractical to separately cement 5 use hollow staybolts. All steamboilers in service each plug in a hole, because it would have to be mustperiodically be inspected to ascertain if any done with care and requireskilled labor, and of the staybolts are broken and whether the boilerthereby increase the cost of installation. Also is safe for itsprescribed pressure. Where hollow there would be danger that anysatisfactory ad- 'staybolts are used, this inspection is made by hesivemight obstruct the porosity of the mate- 10 cleaning and testing theholes in all of the stayrial so as to render it substantially imperviousto bolts to determine that they are clean and open the passage of watertherethrough. throughout the length of the hole, and then plac- Thepresent invention contemplates a plug and ing the boiler underhydrostatic pressure. If any a method of treating the plugs wherein thesurhollow staybolts are broken or even fractured so face of the plug isprovided with a material which 15 that the fracture extends into thehole, the appliincreases the cohesion between the pl a d t cation ofhydrostatic pressure to the boiler will inner wall of the tell-talehole. According to the cause water or moisture to appear in the holes.pr en nv it i mpl h the amount of water, of course, depending on theother material be applied to the porous body extent of the break orfracture. If the holes in which will not lessen the resistance of thatbody 20 the staybolts are not clean the evidence of leak-- to ea pa thePorosity thereof but which age may not be detected, the accumulation ofwill increase the cohesion between the porous madeposit on the inside ofthe hole absorbing or terial and the walls of the hole. closing off theflow of water, particularly where The invention may be readilyunderstood by the fracture is quite small. In some cases, the referenceto the accompanying drawing, in 26 so-called tell-tale hole extendsthroughout the which: full length of the bolt. In other cases, itextends Figure 1 discloses a typical flexible staybolt throughout themajor portion of the length and assembly having a plug at the fireboxend of the not entirely through the bolt. It is good practice hol theplus being t at d n a rda t 30 to drive porous plugs into the holes fromthe firethe present invention; and 3 box end of the bolts when theboiler is ready to Figure 2 is a perspective view of one of the be putinto service. These porous plugs, one form P ugs ma e in accordance Withthe Present invenof which is shown in prior United States Patent tion.

No. 1,428,541, dated September 12, 1922, serve to According to thepresent invention, the porous prevent foreign matter from entering thehole plugs are manufactured according to any well I from the firebox endof the boiler and filling it known method. When the manufacture of theup. At the same time, the plug, being porous, plugs is otherwisecompleted, including the firing will permit the escape of steam and/orwater of the bonded granular material of which they therethrough if thestaybolt subsequently fracare composed, and the shaping, a suitablesizing tures. compound, paste or other form of substance is 40 Thematerial used for making the porous plugs applied to the plugs-andcompletely dried theremust be heat-resisting as well as porous. The on.The sizing or other substance employed bonded granular abrasive materialwhich is genmust be of a character which will not destroy erally usedfor the purpose must have a bond of the porosity of the mass. It must beof a charsuch character that the plugs will not disintegrate acter whichwill dry out thoroughly, and must 45 when they are subjected to thetemperature of be of a character which will leave, when dried, theinside of the firebox. Since the bond is com a deposit on the outside ofthe plug capable of pletely fused in the forming of the plug, the onlyincreasing the cohesion between the plug and the inherent means forholding the plug in the end of inside oi the hole.

the bolt is friction. It has been found in use As a typical example, theplugs after they are 50 that some plugs hold satisfactorily, whereasotherwise ready for use, are immersed in a soluothers will drop out,even though appartion of a waterglass, such as sodium or potassium entlytight in the first instance, after the boiler silicate. The porousmaterial absorbs the waterhas been used for a period of time. This isesglass solution. The plugs are then dried. When pecially so inlocomotive boilers where in addition the plugs are dry a very thindeposit of the 5| 10' rial alone'is relied upon. This has not only beenborne out in actual use, but has been borne out on specially constructedtest panels, such panels .having a large number of staybolts mountedthereon. Arrangements are provided for heating and cooling the panelandan'air hammer is provided for vibratingthe panel. Throughthisarrangement, conditions simulating firebox conditions can be obtainedbutof a morefintensified' order. It. been fo'mid that-porous plugsprocessed asdescribed above, will remain inthe holes on the test panelunder conditions which result infia very great percentage, of theuntreated plugs jarring out. To the eye', however, 'the treated plugs donot differ in appearance from the untreated ones. the amount of.silicate Moreover, the plugs so deposit belnl slllht. treated canbebmlc'en, out of the holes for inspection purposes where necessary asreadily as the untreated onea 'there beingno actual adhesion orcementingsof the plus to the'interior of the hole.

- While the water-soluble silicates make the best material so far.aawrexperlmeatsu it the present time have other materials mayalso be Forexample, the plugs maybe immersed-"in a solution and dried=,-before use.In the subsequent operation of a boiler, the

sugar but the resulting film ofzcarbon neverthelessserves to increasethe cohesion between the plug and the walls of the'hole into which theplug'is driven. Likewise, other organic materials may be used which willalso carbonize as, for a thin solution of gum-tragecanth. solution ofordinary table salt or sodiumchloride may-also'beused. the glaze-,formingj quality of the salt being utilized. Various ceramic slips orcompositions'may also be used. The foregoing are merely typical of agreat many other materials which. maybe used. The material used must beeither dusted onto the exterior of the porous body or if used as asolution must be of a character which will not upon soaking into theporous material, render the same non-porous. The plugs areof relati'velysmall diameter, and hence care must be taken that the material used, ifit soaks into the body of the material will not destroy or seriouslyimpair its porosity. I

In the drawing. .2 designates a typical hollow staybolt having atell-tale hole 3 opening at the firebox end and having a plug 4 drivenintofthe end thereof, the plug beingof a character herein described. InFigure 2, the plug 4 is shown detached from the staybolt. It ispreferably slightly tapered to facilitate its being entered into thehole of the staybolt and driven in.

The material used for treatingthe plugs mus be a material which can bedried so that the plugs after being-manufactured and treated, can

be shipped in a dry state to the user. a

It will be understood that various changes and modifications may be madein the invention within the scopeof the following claims.

We claim: A l. A porous plug for staybolts comprising a refractory bodyof a porous chai acte'r having a surface coating of a materialthereon ofa glazelik e nature for increasing the frictional'co'ntact ,between theplug'and the wall of the hole in the v 2. Aporou's plug for stayboltscomprising a refractory body of'a" porous characterhaving .a

water-soluble silicate applied to the outer'surfaces thereof; 3. Aporous plug foista' fractory body of a ro "its comprising a retheporosity of the plug a whole and which increases the cohesion betweenthe plug and the hold of the staybolt into which the plug is entered. r

4. The method. of treating porous plugs'for use in closing thetelltalaholes of, boiler staybolts character having a dried coatingformihg a surface film thereover of alcharacter which does notdetrimentally' affect which comprisesimmersing the plugs in a solu-"tioncapable of leaving afdepositon the porous materiaiof acharacter-which increases the cohesion between'the plu'g and theholeinto which the plug is drivenbiitwhich does not appreciably affect theporosity of theplug. Q

5. Themethod of treating. porous plugs for use in closing the telltaleholes'lof' boiler. ,staybolts which comprises immersing the plugs ,in aso1ution of a water-soluble silicate'and thereafter drying the plugs. vV

mores.

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